Method for transferring cargo between vessel and dock

ABSTRACT

A transfer frame mounted on a dock and formed with a pair of side by side elevator towers extending upwardly to about the level of the uppermost container on a ship to be unloaded and over on their sides facing such ship. Elevators are mounted in the towers for up and down movement to transfer cargo from the higher elevation to a lower elevation to be fed onto a feed conveyor. An overhead crane includes a boom projecting over the towers and over the containers on the ship. A trolley is mounted on the boom for shifting between the tower and ship and includes a hoist for hoisting cargo containers from the ship for transfer along under the beam and through such opening side of the tower to a position over one of the elevator platforms for being lowered a short distance thereto. Simultaneously, an outgoing container may be moved onto the other elevator and elevated for pick up by the hoist after the discharge container is released. The method of the present invention involves transfer of the containers via the trolley by elevating such containers slightly from their pick up points and transporting them along the boom to be loaded on the elevator platforms previously disposed at essentially at the same height and unloaded on the elevator platform at substantially the same elevation as the pick up point from the ship.

This is a divisional of copending application Ser. No. 059,263 filed on6/5/87, now U.S. Pat. No. 4,872,798.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for rapidly loading andunloading cargo containers from a vessel, such as a ship andtransporting them to a storage or ground transport area.

2. Description of the Prior Art

In the past decade and a half, much of the marine cargo industry hasbeen converted to containerized cargo wherein products to be shipped areloaded in large containers of a size approaching that of a conventionaltruck cargo van and then loading the filled containers themselves on theships. Such a containerized approach has proven popular and allows forloading and unloading thereof inland of the dock and subsequenttransportation of such containers to and from the dock area for loadingon a vessel. This allows for economical loading of the individualcontainers at a rate dictated by convenience and uninfluenced by thesignificant cost of lay time for a sea going vessel which must be atdock for the final loading process. Likewise, when such containers areunloaded from the vessel they may be transported by truck or train,fully loaded, to their destination where the unloading process of thecontainers themselves will take place.

Due to the fact that the hourly cost of a ship in harbor isconsiderable, many efforts have been made to provide for rapid loadingand discharging of such cargo containers from the ship to therebyminimize the time a ship must remain in port for discharge and loading.One such cargo handling apparatus in common use utilizes a hoist mountedon a trolley carried on an overhead boom of a hammer head crane whereinthe hoist may be attached to a container to hoist such cargo up to thetrolley to be transported across the boom to be disposed over thehatchway to the ship's hold. The hoist is then actuated to lower thecontainer into the hold. The process is then repeated until the ship'shold is filled. A hatch cover is then placed in position over thehatchway and additional containers then stacked on the hatch to a heightof, for instance, four to five containers and seven to twelveathwartship, each container having a height on the order of eight feet.

Such system suffers the shortcoming that the trolley must be positionedover the container on the dock, the hoist lowered a distance of, forinstance, 150 feet and attached to the container. The container mustthen be hoisted upwardly the same distance of 50-65 feet, and thetrolley then transported out the boom and over the ship. Again, there,the container is lowered into the ship's hold or onto deck of the shipand the process repeated. Unloading of the ship is just the reverse.That is, the containers are picked up, first off the stack loaded on theship's deck, the hatch cover removed and then the containers removedfrom the hold. It will be appreciated that the time consumed each timethe hoist is raised and lowered is significant and that the trolley isfully occupied by a single container during the entire transferprocedure. In addition to the time consumption, such systems typicallyrequire a substantial amount of support equipment and personnel. Thatis, a crane driver is required for the trolley on the hammerhead crane,ship deckmen are required for attaching and detaching the cargo hoist,tractor or truck drivers are required for sequentially moving trucks,bogies or straddle trucks onto the dock area for receiving the cargocontainers and removing them from the hoist area during the dischargeoperation. The need for more economical and efficient systems have ledto many different proposals.

One such system involves a pair vertical conveyors, one dock side andanother ship side, with a horizontal conveyor therebetween forautomatically transferring pelletized loads up from the ship's hold,across the horizontal conveyor and down to the dock. An arrangement ofthis type is shown in U.S. Pat. No. 1,525,950 to Prescott. Such devices,while acceptable for their intended use, suffer the shortcoming thatthey cannot practically handle large containers typically used inmaritime shipping and that their operation is hindered by surge and riseand fall of the tide which results in misalignment of the conveyors andrenders transfer from one conveyor to the other impossible.

Other devices proposed include a horizontal hammerhead crane carrying atrolley mounting a hoist which is intended to pick up cargo from theship to be lowered into a vertical elevator for subsequent transfer. Adevice of this type is shown in U.S. Pat. No. 4,431,359 to Toniolo.Again, while satisfactory for its intended purpose, such devices sufferthe shortcoming that the elevators are not configured and arranged toreceive the cargo containers sideways thereonto from the hoist withoutsubstantial lowering thereof each time transfer is made thus consumingundue time. Accordingly, substantial time is lost on each trip becauseof the necessity that the hoist raise the container to the full heightso the trolley may carry it to a position disposed over the elevators sothe cargo may be lowered some distance thereonto.

Accordingly, there exists a need a cargo handling system which providesfor efficient movement of the trolley on the hammerhead crane with aminimum of down time for retrieving cargo containers from the ship'sdeck at approximately the elevation of the cargo's initial storage andtransfer substantially horizontally directly to elevators located atabout the same height so that vertical travel of the hoist is minimizedto make most efficient use of the trolley.

SUMMARY OF THE INVENTION

The invention is intended to be used with a hammerhead crane having ahorizontal boom extending from a point over cargo containers stacked ona ship's deck to a dock side tower open on the side facing the ship andmounting an elevator having a support platform which may be raised tothe various levels corresponding with the horizontal levels of thecontainers on the ship to be unloaded. The trolley and hoist may thus beoperated to transfer the containers to the elevator platform with only aminimum of vertical travel of the containers. A conveyor is provided atthe foot of the elevator for transferring the cargo from the loweredelevator platform for storage or loading onto ground transportation,such as trucks or railroad cars. On the return trip the hoist may pickup a container from a loading elevator and transport it to the ship forloading thus utilizing travel in each direction of the trolley.

Other objects and features of the invention will become apparent fromconsideration of the following description taken in connection with theaccompanying drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a broken elevational view of a cargo transfer apparatusembodying the present invention;

FIG. 2 is a top plan view taken along the line 2--2 of FIG. 1;

FIG. 3 is a side view taken along the line 3--3 of FIG. 1;

FIG. 4 is a detail view, in enlarged scale, taken from the circledesignated 4 in FIG. 2;

FIG. 5 is a broken view, in enlarged scale, of an elevator cableincorporated in the elevator shown in FIG. 3;

FIG. 6 is a detail view, in enlarged scale, taken from the circle 6--6in FIG. 2;

FIG. 7 is a transverse section view taken along the line 7--7 of FIG. 6;

FIG. 8 is a broken top plan, in enlarged scale, showing the conveyorrollers depicted in FIG. 2.;

FIG. 9 is an elevational sectional view, in enlarged scale, of a queuingrail system which is utilized with the system shown in FIG. 1; and

FIG. 10 is a diagrammatic view of a staging system employed with thetransfer apparatus shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT a. Overview

The cargo transfer system of the present invention includes, generally,a hammerhead crane 21 carrying a trolley 23 mounting a pair of hoists 24for travel from a position over the top layer of cargo containers 25stacked on the deck of a ship 27 to a location over a vertical tower 31incorporated in a mobile transfer 32 mounted for travel along thepierhead 52 of the dock 51. The vertical tower 31 mounts a pair ofloading and discharge elevators, generally designated 33 and 35,respectively, which are shown for the purposes of this disclosure aselevatable from a position at least level with the bottom of the toplayer of containers to a position with respective load and dischargeaccumulator conveyors, generally designated 39 and 37, which feeds thecontainers away from or onto the support elevators 33 and 35, dependingon whether the containers are being loaded or unloaded. Consequently,the hoist 24 may be activated to pick up a container 25 from the stackon the ship, the trolley 23 activated to carry it over the tower 31 asthe loading elevator 33 reaches to its uppermost position shown inbroken line in FIG. 1 such that it is at a level to receive thecontainer 25 without substantial lowering thereof. After unloading, thetroller 23 may continue on over the elevator 35 which has been raised toits elevated position to pick up a container 25' from that elevator, tobe raised and transported back to the vessel for loading at a locationfor storage when the ship gets underway.

A vessel 27 coming loaded into port is typically moored along a dock orquay 51 (FIG. 1) and the unloading procedure undertaken to transfer thecontainers 25 from such vessel onto the dock. Once the ship has beenfully or partially unloaded, a new load of containers 25' may be loadedon for transportation to another port. During this entire process, thevessel itself is subject to elevational shifting and movement induced bytide and surge.

b. The Crane 21 and Transfer 32

The hammerhead crane 21 may be of conventional construction and may besupported in cantilever fashion from a tower (not shown) on the dock 51.The crane includes a horizontal boom 53 mounting a track onto which thewheels of the troller 23 rides. The trolley itself includes a pair ofcoordinated hoists 24 carrying a spreader 57 therebetween. Dependingfrom the opposite corners of the spreader are grabbers 59 for grabbingthe top corners of the containers 25 for holding such container whilethey are hoisted to their elevated positions as described hereinafter.

The dockside transfer 32 is carried on wheels which ride on tracks 56and 58 (FIGS. 1 and 10) and is formed with the vertical tower 31(FIG. 1) which is of sufficient height to extend to the horizontal levelof the bottom of the container 25 stacked on the uppermost layer. Thetower 31 is formed with a pair of elevator shafts 63 and 65 (FIG. 2)having sufficient height to accommodate the overall length of thecontainers 25. Such shafts are open throughout their height on theirsides facing the ship to form respective vertical openings definingdoorways 60 and 62 (FIG. 2) for receipt therethrough of the containers25 and 25' suspended from the hoists 24. The elevator shafts 63 and 65receive respective rectangular floor frames 64 and 66 which act asrespective container supports. Such elevator floors are formed at theiropposite ends with pairs of parallel cross bars 67 and 69 whichprojecting laterally away from the vessel 27 and between which aremounted powered rollers 71 disposed in rows to define roller beds,generally designated 70 and 72 adapted to carry the containers 25 and25' and drive them onto and off the elevators.

The container support platforms 64 and 66 mount at their respectivecorners, in perpendicular relationship, rollers 75 and 77 (FIG. 4) whichride on the corner of vertical posts 81 and guide flanges 83 formed atthe corners of the elevator shafts 63 and 65 to thus guide such supportsas they travel upwardly and downwardly in the elevator shafts.

By the way of illustration herein, an elevator drive in the form ofpullies 87 (FIG. 5) mounted at the top of the tower 63 have ropes 91threaded thereover with one end 95 being connected to an elevator floorsupport 66 and the opposite end being wound on a power driven spool 99.It will be appreciated that separate drives are provided for each of theelevators 33 and 35 such that they may be shifted verticallyindependently of one another.

Referring to FIGS. 1-3, the transfer 32 includes a frame formed with ahorizontally disposed feed section projecting inland from the bottom ofthe tower 31 and formed with pairs of laterally disposed parallel rowsof powered rollers 105 and 107 (FIG. 2) defining the feed tracks in theform of roller beds 37 and 39 leading away from the elevator tower 31.Referring to FIG. 8, the rollers 105 and 107 are formed with bearingsections 111, guide flanges 112 and four axially spaced apart drivenchain sprockets 115, 117, 119 and 121. Sprockets of three adjacentrollers 105 are connected together by means of endless sprocket chains125, 127, 129 and 131. The respective chains 125-131 are arranged instaggered relationship such that each chain is drivingly connected withat least the top sides of the driven chain sprockets of three rollers(FIG. 8) with the bottom run of pairs of laterally adjacent chains beingthreaded over drive sprockets such as the sprockets 141 and 143 shown inFIG. 7 and mounted on a common shaft 145 to thus afford parallel driveto each such roller.

In this regard, the drive chains of adjacent pair of rollers 105 aretrained over drive sprockets 141 and 143 of respective drive shafts 145coupled through a gear box to a drive motor 147. With this arrangement,each conveyor roller 105 is driven by two different drive chains suchthat should one chain 127 break, the other chain 129 will continue todrive those rollers.

c. Queuing Trucks 157 and 159 And Staging Yard 170

Referring to FIGS. 9 and 10, a plurality of transfers 32 may bepositioned along the dock 51 adjacent the bulkhead 52 for conveying thecontainers 25 therefrom. As shown in FIG. 9, a trench 151 extendslongitudinally of the dock at the end of the respective feed andtransfer conveyors 37 and 39. Mounted in the trench 151 are two pairs ofqueuing rails 153 and 155 mounting thereon transfer trucks 157 and 159.Mounted from the trucks 157 and 159 by means of respective scissorsjacks 161 and 163 are respective truck beds 165 and 167 which mountthereon powered conveyor roller beds 169 and 171. Located on the side ofthe trench 151, opposite the transfers 32 is a staging yard 170 formedby a plurality of laterally extending parallel staging conveyors 175(FIGS. 9 and 10) which mount powered conveyor rollers 177 operative todrive the containers longitudinally therealong. With continued referenceto FIG. 10, queuing trucks 189 and 191 similar the trucks 157 and 159are located in a trench at the opposite ends of such separator tracksand travel on respective rails 193 and 195 extending transversely ofsuch staging conveyors. Such trucks 181 and 189 travel along the ends ofthe staging conveyors 175 for selective receipt or deposit of containers25 from or on to such conveyors to selectively transport such containersto a location under a train loading crane 21 to be describedhereinafter.

Paralleling the queuing tracks 193 and 195 are railroad tracks 197 overwhich is disposed an overhead crane, generally designated 201, whichtravels back and forth along such tracks and carries a trolley 207 toselectively receive containers 25 from the trucks 189 and 191 totransfer them to rail cars on the railroad tracks 197. Conversely, itmay receive containers 25' from such railroad cars to be transferredinto the staging yard 170 for loading onto the ship as will be describedhereinafter.

d. Unloading Incoming Containers 25

In operation, a container ship 27 arriving in port, will typically beloaded, the hold being loaded with containers 25 and additionalcontainers stacked on the deck as shown in FIG. 1. The features of thepresent invention may be appreciated by considering an unloading shipdischarge operation. It will be appreciated that once the ship 27 isbrought into mooring position along the pier head 52 of the dock 51(FIG. 1), one or more of the transfers 32 may be moved into positionspaced longitudinally along the side of the ship under appropriatelyspaced hammerhead cranes 21. It will be appreciated by those skilled inthe art that the controls for the transfers 31, rollers of the variousroller beds on the elevators 33 and 35, loading and discharge rollerbeds 37 and 39, elevator motor, queuing trucks 157 and 159, roller beds175 of the staging yard 170, queuing trucks 189 and 191 and transfercrane 201 may all be controlled by a computer system which may beprogrammed in advance of the ship's arrival with relevant informationrelating to the incoming cargo, destination thereof and train carslocated on the train tracks 197, as well as information on containers25' to be loaded.

Once the ship 27 has been moored and the hammerhead cranes 21 andtransfers 32 shifted into position, the trolleys 23 may be actuated todrive such trolleys outwardly over the containers 25 stacked on the deckof the ship 27 to commence the unloading operation. By way of example,the process may start with the container 25 (shown in phantom) locatedin the upper righthand corner, as viewed in FIG. 1. For that transfer,the hoists 24 may be activated to lower the spreader 57 a relativelyshort distance to enable the grabbers 59 to grab the corners of thecontainer 25 being unloaded. The hoists 24 may then be actuated to raisethe container two or three inches and the trolley actuated to travel tothe right along the boom 53 a distance of, for instance 25 feet, totransport the container 25 through the open side 60 of the tower 31 to alocation inwardly above the elevator platform 64. It will be appreciatedthat, in the meantime, the elevator has been actuated to raise thedischarge elevator platform 64 to the broken line position shown inFIG. 1. By then actuating the hoists 24 to lower the spreader bar 57 twoor three inches to allow the container to come to rest on the platform64, the grabbers may be actuated to release the container 25 to free itto rest on the elevator roller bed 70 of the platform 64. The trolley 23may then be actuated to move back along the boom over the ship to graspthe next container. Concurrently the elevator 33 is actuated to lowerthe platform 64 to its lowered position in horizontal alignment with thedischarge conveyor 39 and the roller bed 70 then actuated to drive thecontainer to the right on to the discharge roller bed 39. It will beappreciated that the roller bed 39 is then actuated to advance thedischarge container 25 to the right along the roller bed, it beingappreciated that such roller bed may incorporate a series of sensors andcontrols such that the containers may be stored thereon awaitingdischarge to a queuing truck 157 (FIGS. 1 and 9). Such sensors andcontrols are well known to those skilled in the art so are not describedhere.

Returning now to the trolley 23, it will be appreciated that suchtrolley has meanwhile been shifted to the left along the boom 53 to pickup another container 25 and return to a position over the elevator 33 tomeet the upcoming unloaded platform 64. This process is repeated untilan area of the deck or the hold has been sufficiently unloaded toreceive incoming cargo.

e. Loading Outgoing Containers 25'

When loading of the outgoing containers 25' is to be commenced, theoutgoing elevator 35 is actuated to lower the platform 66 to the levelof the outgoing transfer roller bed 37 such that the bed 37 may beactuated to drive an outgoing container 25' onto the roller bed 72 ofthe elevator platform 66. The elevator 35 is then actuated to raise theplatform 66 to approximately the position shown in FIG. 1. When thecontainer 25 being discharged has been unloaded from the trolley 23, thetrolley may then be actuated to move six to ten feet to the right toposition the spreader 57 over the outgoing container 25' and the hoist24 actuated to lower the spreader to enable the grabbers 59 to grab thecorners of the outgoing container 25'. The hoists 24 are again actuatedto raise the container 25' and the trolley actuated to commence movingleftward along the boom 53. It will be appreciated that after initialhoisting of the container 25', hoisting thereof may be continued as thetrolley 23 travels to the left over the discharge elevator platform 64descending down in the elevator shaft 63. It will be appreciated that,in the case of a computer control system, the travel orientation andstopping of the elevators 33 and 35 may be programmed to mosteconomically and efficiently allow for minimum travel of the hoist 24 inmaking a transfer between one and the other, all dependent on theelevation at which containers are being loaded and discharged from theship 27. In any event, the outgoing container 25' will be advanced overthe ship, the hoists 24 actuated to lower the container onto the ship,the grabbers 59 released and the hoists and trolley 23 and 24 actuatedto move into position over a container 25 to be discharged and theprocess repeated.

f. Queuing And Transferring

Referring to FIGS. 9 and 10, the discharged containers 25 aresequentially received on queuing trucks 157 and 159 travelling in thetrench 151 past the end of the transfers 32 for travel along the trench151 to a selected transfer roller bed 175 in the transfer yard 170 fortemporary storage and/or direct advancement to railroad queuing trucks189 and 191 disposed on the tracks 193 and 195 at the opposite end ofsuch transfer beds 175. Thus, it will be appreciated that the respectivetrucks 157 may be aligned with the ends of the respective dischargetransfer roller beds 39 to receive the containers 25, final positioningof the container on the truck bed 165 being achieved by the poweredroller bed 168. The loaded queuing truck 157 may then be advanced alongthe trench 151 into alignment with the end of the selected stagingconveyor 175. The adjacent truck 159 may be simultaneously moved intoposition beside the truck 157, the elevating jacks 161 and 163 beingactuated to maintain the roller beds 168 and 172 in horizontal alignmentwith one another and in horizontal alignment with the particularconveyor 175 to which the container 25 is to be transferred. If bothbeds 168 and 172 are loaded, the container 25 on the bed 172 will beadvanced to the conveyor 175, followed by the container 25 supported onthe bed 168. In the event only the bed 168 is loaded, the back containerwill merely be transferred across the roller bed 172 to the conveyor bed175. The containers may then be stored on the staging conveyors 175until loading of a train or trains on the tracks 197 is to be commenced.

When the train cars have been moved into position, the containers 25 maybe received off from the ends of the transfer conveyor beds 175 and ontothe trucks 191 for transfer laterally to the cars 189 and to be pickedup by the trolley 207 on the overhead crane 201 to be transferred alongthe boom of such crane for deposit on the respective rail cars.

It will be appreciated that a section of the staging yard 170 may beassigned to cargo to be loaded onto the ship 27. For that cargo, thecontainers 25 may be advanced along the roller beds of the stagingconveyors 175 and onto the queuing trucks 159 shifted into alignmentwith the ends of such conveyors. The loaded queuing truck 159 may thenbe transferred along the rails 155 in the trench 151 into alignment withthe end of the particular loading roller bed 37 (FIG. 9) of the transfer32 to receive such conveyor. A parallel queuing truck 157 will be alsomoved into position between the transfer feed bed 37 and the truck 159and the beds 168 and 172 of such trucks elevated by means of the jacks161 to a level corresponding with the level of the feed conveyor 37. Theroller beds 172 and 168 are then actuated to transfer the container 25'onto the feed roller bed 37 to be eventually transferred onto theelevator 35 as described hereinabove.

It will be appreciated that each of the aforedescribed operations willbe coordinated with one another and will be tied into a conventionalcomputer program to enable the most efficient coordination ofoperations. The loading and unloading procedure may be preprogrammedprior to the ship arriving in harbor such that coordination of thetrolley 23, hoists 24, elevators 33 and 35, roller beds 37 and 39,queuing trucks 157, 159, 189 and 191 and staging conveyors 175 andpossibly even the overhead transfer crane 201 are all coordinated inmovement to thus assure the greatest degree of efficiency and minimumlay time for the vessel 27. In this regard, it has been demonstratedthat with conventional methods, as described in the prior art section ofthis specification, only approximately 20 to 25 containers are loaded orunloaded per hour. The attendant equipment and personnel necessary tohandle that volume of transfer is considerable. Conventional systems donot typically have capability of unloading directly from the ship torail or truck as provided for with the present invention. Rather, eachcontainer is unloaded, stored and then rehandled for staging at dockside.

With the present system a container can be loaded or unloaded in between12 and 20 seconds, and in no case more than 30 seconds, with an overallcapacity on the average of about 120 containers per hour. Additionally,the support equipment and personnel may be cut approximately in half.This more than doubles the efficiency of loading and unloading,represents an increase in productivity, reduction in the energyconsumed, reduces air pollution, adds to safety conditions at the docksand, by transferring directly to the train, reduces highway traffic.These benefits are provided with a relatively economical and reliablesystem which is relatively inexpensive to manufacture and install.

Various modifications and changes may be made with regard to theforegoing detailed description without departing from the spirit of theinvention.

I claim:
 1. A method for transferring containers between a dock and avessel positioned adjacent said dock, comprising the steps of:selectingan overhead boom of a type which horizontally projects from a positionover said dock to a position over said vessel and which includes atrolley, shiftable between said dock and said vessel, said trolleyfurther including a hoist capable of releasably grasping and raising andlowering individual ones of said containers while conveying it along apathway from said vessel to said dock; selecting a dockside transferapparatus positioned on said dock below said boom and of the typeincluding a first container support raisable from a lowered positionproximate said dock to a raised position and laterally accessible bysaid containers throughout the elevations from said lowered to saidraised positions as said individual containers are conveyed along saidpathway; retrieving a first container by shifting said trolley alongsaid boom to a position above said first container on or in said vessel,lowering said hoist to grasp said first container and raising said firstcontainer to a level sufficient to clear said vessel; concurrent withsaid retrieving step, raising said first container support to a transferelevation substantially level with the retrieved first container;shifting said trolley to carry said first container along said pathwayto position it directly on said first container support; releasing saidfirst container from said hoist; lowering said first container supportto said dock and offloading said first container from said firstcontainer support to said dock; and shifting said trolley along saidboom to a position over said vessel.
 2. A method for transferringcontainers according to claim 1 wherein:said step of selecting saidtransfer apparatus includes the step of selecting a transfer apparatusof the type including a second container support raisable from a loweredposition to a raised position and laterally accessible by saidcontainers throughout the elevations therebetween; simultaneously withsaid step of raising said first container support, raising said secondcontainer support, supporting a second container, to substantially saidtransfer elevation; and after releasing said first container from saidhoist and during said lowering step, shifting said trolley to a positionover said second container; grasping said second container; and shiftingsaid trolley to position said second container over said vessel.
 3. Amethod for transferring containers according to claim 1 thatincludes:the step of repeating the steps set forth in claim 1 fortransferring a plurality of containers from said vessel to said dock;receiving and accumulating such off loaded containers on an accumulatorconveyor on said dock until a number of said containers have beenaccumulated; and conveying said containers away.